To publish feature services that reference your data sources, create maps in ArcGIS Pro or ArcMap that contain the feature data you need in the service. You can then publish a service from either of these apps. In ArcMap, you have the option to create a service definition file rather than publish a feature service. You can later upload the service definition file to ArcGIS Server Manager and publish the feature service there.
Publish from ArcGIS Pro
In an ArcGIS Pro project, create a map that contains the data you want to publish. Register your data sources with one of your portal's federated servers and publish a feature layer that references the registered data.
See Web feature layer in the ArcGIS Pro help for instructions on publishing a feature layer that references registered data.
Publish from ArcMap
Author an ArcMap document that contains the data you want to publish. Register your data sources with your ArcGIS GIS Server site, and publish a map service with feature access enabled to a GIS Server publisher connection.
See Publish a feature service from ArcMap for instructions.